Objective identification method for tropical cyclone landfall information

This study projects the changes in tropical cyclone (TC) landfalls in the western North Pacific under shared socioeconomic pathway (SSPs) scenarios during the TC peak season by using low‐resolution global climate models participating in the Coupled Model Intercomparison Project phase 6 (CMIP6). Projections are based on the relationship between mid‐ and lower‐level atmospheric circulation and TC landfall frequency during the historical period from 1985 to 2014 and the future climate period from 2015 to 2100. The landfall areas for TCs are divided into northern East Asia (NEA), middle East Asia (MEA) and southern East Asia (SEA); the TC peak seasons are July–September for NEA and MEA, and July–November for SEA. To evaluate reproducibility, both ensemble and individual model outputs for mid‐ and lower‐level atmospheric circulations associated with TC landfall in each East Asian subregion are compared to the reanalysis. An ensemble of seven models with stable results for all three regions is more reasonable in simulating atmospheric circulation patterns than an ensemble of all CMIP6 models. The findings suggest that TC landfall is projected to increase by about 12% and 32% in NEA and MEA, respectively, in the late 21st century under the SSP5‐8.5 scenario compared to the historical period, while decreasing by 13% in SEA. These changes are consistent under both warming scenarios, and are more pronounced in the SSP5‐8.5 scenario compared to SSP1‐2.6, particularly in the later period of this century. An analysis of future atmospheric circulations suggests that global warming will weaken the western North Pacific subtropical high and cause its boundary to retreat eastward. This will lead to changes in the steering flow, which is closely related to TC tracks, resulting in TC landfalls to increase or decrease depending on the East Asian subregion.

This study develops a statistical‐dynamical seasonal typhoon forecast model (SDTFM) that utilizes the statistical correlation between East Asia (EA) tropical cyclone (TC) landfall and atmospheric circulation predicted by a coupled general circulation model for seasonal prediction and its predictability is verified. A total of 40 ensemble members produced through different data assimilation and time‐lag methods introduced as a way to reduce the initial condition error and model uncertainty enabled the development of the new SDTFM. According to the results, the SDTFM developed in this study showed significant predictability in TC landfall prediction when using the month of May for the initial conditions for the entire East Asia (EEA) and its three sub‐domains: Northern East Asia (NEA), Middle East Asia (MEA), and Southern East Asia (SEA). The predicted TC season is July–September (JAS), and only for SEA, including South China, the Philippines, and Vietnam, it is July–November (JASON) considering the relatively long landfall period. The models developed for each domain significantly predict the interannual variability of TC landfall at the 99% confidence level. The cross‐validated results are still significant at the 99% confidence level in NEA and SEA and the 95% confidence level in MEA and EEA.

Post-Tropical Cyclones (PTCs) can cause extensive damage across Europe through extreme winds and heavy precipitation. With increasing sea surface temperatures, tropical cyclones (TC) may form and travel further polewards and eastwards than observed historically. Recent work has suggested that the frequency of intense Europe-impacting PTCs may increase substantially in the future. Using an objective feature tracking scheme and TC identification method, we track and identify the full lifecycle of TCs in the North Atlantic in five CMIP6 climate models in the historical (1984–2014) period and in the future under the SSP5-85 scenario (2069–2099). These five models are selected based on their ability to simulate similar TC frequency similar to observed in the North Atlantic, although model deficiencies remain. We find no robust changes in Europe-impacting PTC frequency or intensity in the future. This is because two competing factors – a significant decrease in TC frequency of 30–60 %, and an increase in the proportion of TCs reaching Europe – are approximately the same size. The projected increase in the proportion of TCs reaching Europe is largely driven by an increase in the likelihood of recurvature and is consistent with projected decreases in vertical wind shear and increases in potential intensity along the US East Coast in the future. The projected increased likelihood of recurvature is also associated with a shift in TC genesis away from the main development region, where model biases cause very few TCs to recurve. This study indicates that large uncertainties surround future Europe-impacting PTCs and provides a framework for evaluating PTCs in future generations of climate models.

This study investigates how tropical cyclone (TC) tracks and landfalls are modulated by the two major components of the intraseasonal oscillation (ISO), the 30–60-day Madden–Julian oscillation (MJO) and the 10–20-day quasi-biweekly oscillation (QBWO). In the convective phases of the MJO (phases 7 + 8 and 1 + 2), the western North Pacific Ocean (WNP) is mainly clustered with westward- and northwestward-moving TCs. The strong easterlies (southeasterlies) in the southern flank of the subtropical high lead to an increase in TC activity and landfalls in the Philippines and Vietnam (China and Japan) in phase 7 + 8 (phase 1 + 2). In the nonconvective phases (phases 3 + 4 and 5 + 6), TCs change from the original straight-moving type to the recurving type, such that the tendency for landfalls is significantly reduced. The QBWO, on the other hand, has a significant influence on TC landfalls in the Philippines and Japan. The strengthening of the subtropical high in phase 1 + 2 favors the development of westward-moving TCs and results in an increase in landfalls in the Philippines, while in phase 3 + 4 (phase 5 + 6), there is an increase (decrease) in TC activity and landfalls in Japan because of changes in genesis locations and large-scale circulations. The results herein suggest that both the MJO and QBWO exert distinctive impacts on TCs in the WNP.

Numerous studies focus on the impacts of ENSO diversity on tropical cyclone (TC) activities in the western North Pacific (WNP). In recent years, there is a growing threat of landfalling and northward-moving TCs in East Asia, accompanying an increase in central Pacific (CP) El Niño. Here, we aim to discover variations in landfalling TCs during various types of CP El Niño (CP-I and CP-II El Niño). It is found that significant changes in landfalling and going northward TCs over East Asia north 20°N are modulated by CP-I El Niño. During CP-I El Niño, TCs tend to landfall more often over the mainland of China with longer duration, moving distance, and stronger power dissipation index (PDI) after landfall and increased TC-induced rainfall, due to favorable conditions (beneficial steering flow, weak vertical wind shear, increased specific humidity, increased soil moisture, and temperature), especially significant over the northeastern part. The situation over the mainland of China is reversed during eastern Pacific (EP) El Niño and CP-II El Niño, with a significant decrease in the characteristics with corresponding unfavorable environments. Over the Korean Peninsula and Japan, the frequency of TC landfalls, as well as the duration and the moving distance after landfall, exhibits greater levels during CP-I and CP-II El Niño than during EP El Niño due to favorable steering flow, and thus, TC-induced rainfall enhances correspondingly. Regarding the PDI over the Korean Peninsula and Japan, it remains relatively consistent across all El Niño types. However, a notable increase in the PDI during EP El Niño could be attributed to the higher intensity of TCs prior to landfall.

The world record for a storm surge is 13 m, occurring during landfall of Tropical Cyclone (TC) Mahina in northeast Australia, March 1899. The central pressure of this cyclone has been reported as 914 hPa as measured by a ship's barometers during passage of the eye. The accuracy of these measurements is poor, as the only source for this information has been thirdhand accounts in an anonymously authored report. Modeling of this event, at 914 hPa, also suggests that the highest storm surge that could have been generated at the site of landfall of TC Mahina is approximately 5 m, well short of the reported 13 m. This study reexamined the evidence for this event and based on archived firsthand accounts, it seems more likely that the central pressure of this event was 880 hPa, which when modeled can generate a storm surge over 9 m and a total inundation (surge plus tide and wave action) of approximately 13 m. The central pressure of TC Mahina may also be the lowest recorded for a Southern Hemisphere tropical cyc...

A pilot study evaluated a computer-based method for comparing digital dental images, utilizing a registration algorithm to correct for variations in projection geometry between images prior to a subtraction analysis. A numerical assessment of similarity was generated for pairs of images. Using well-controlled laboratory settings, the method was evaluated as to its ability to identify the correct specimen with positive results. A subsequent clinical study examined longitudinal radiographic examinations of selected anatomical areas on 47 patients, analyzing the computer-based method in making the correct identification based upon a threshold level of similarity. The results showed that at a threshold of 0.855, there were two false negative and two false positive identifications out of 957 analyses. Based on these initial findings, 25 dental records having two sets of full mouth series of radiographs were selected. The radiographs were digitized and grouped into six anatomical regions. The more recent set of films served as postmortem images. Each postmortem image was analyzed against all other images within the region. Images were registered to correct for differences in projection geometry prior to analysis. An area of interest was selected to assess image similarity. Analysis of variance was used to determine that there was a significant difference between images from the same individual and those from different individuals. Results showed that the threshold level of concordance will vary with the anatomical region of the mouth examined. This method may provide the most objective and reliable method for postmortem dental identification using intra-oral images.

The present study identifies a significant influence of the sea surface temperature gradient (SSTG) between the tropical Indian Ocean (TIO; 15°S–15°N, 40°–90°E) and the western Pacific warm pool (WWP; 0°–15°N, 125°–155°E) in boreal spring on tropical cyclone (TC) landfall frequency in mainland China in boreal summer. During the period 1979–2015, a positive spring SSTG induces a zonal inter-basin circulation anomaly with lower-level convergence, mid-tropospheric ascendance and upper-level divergence over the west-central TIO, and the opposite situation over the WWP, which produces lower-level anomalous easterlies and upper-level anomalous westerlies between the TIO and WWP. This zonal circulation anomaly further warms the west-central TIO by driving warm water westward and cools the WWP by inducing local upwelling, which facilitates the persistence of the anomaly until the summer. Consequently, lower-level negative vorticity, strong vertical wind shear and lower-level anticyclonic anomalies prevail over most of the western North Pacific (WNP), which decreases the TC genesis frequency. Meanwhile, there is an anomalous mid-tropospheric anticyclone over the main WNP TC genesis region, meaning a westerly anomaly dominates over coastal regions of mainland China, which is unfavorable for steering TCs to make landfall in mainland China during summer. This implies that the spring SSTG may act as a potential indicator for TC landfall frequency in mainland China.

Spatial patterns of tropical cyclone tornadoes (TCTs), and their relationship to patterns of mesoscale predictors within U.S. landfalling tropical cyclones (LTCs) are investigated using multicase composites from 27 years of reanalysis data (1995–2021). For 72 cases of LTCs with wide-ranging TC intensities at landfall, daytime TCT frequency maxima are found in the northeast, right-front, and downshear-right quadrants when their composites are constructed in ground-relative, TC-heading relative, and environmental shear relative coordinates, respectively. TCT maxima are located near maxima of 10-m–700-hPa bulk wind difference (BWD), which are enhanced by the TC circulation. This proxy for bulk vertical shear in roughly the lowest 3 km is among the best predictors of maximum TCT frequency. Relative to other times, the position of maximum TCT frequency during the afternoon shifts ∼100 km outward from the LTC center toward larger MLCAPE values. Composites containing the strongest LTCs have the strongest maximum 10-m–700-hPa and 10-m–500-hPa BWDs (∼20 m s−1) with nearby maximum frequencies of TCTs. Corresponding composites containing weaker LTCs but still many TCTs, had bulk vertical shear values that were ∼20% smaller (∼16 m s−1). Additional composites of cases having similarly weak average LTC strength at landfall, but few or no TCTs, had both maximum bulk vertical shears that were an additional ∼20% lower (∼12 m s−1) and smaller MLCAPE. TCT environments occurring well inland are distinguished from others by having stronger westerly shear and a west–east-oriented baroclinic zone (i.e., north–south temperature gradient) that enhances mesoscale ascent and deep convection on the LTC’s east side.

The occurrence and impacts of tropical cyclones in the Southwest (SW) Indian Ocean were investigated over five cyclone seasons (November to April) between 2018/19 and 2022/23. Data describing cyclone characteristics, affected populations and economic losses from cyclone landfalls in Madagascar and Mozambique were extracted from the African Risk Capacity (ARC)’s Tropical Cyclone Explorer (TCE) software. Of 56 cyclones that formed in the region, 27 landfalls occurred with an average of 2.8 per season in Madagascar and 2.6 in Mozambique, mainly in January and February of each year. Most cyclone landfalls in Madagascar were categorized as moderate tropical storms (MTS, 43 %) and intense tropical cyclones (ITC, 22 %). In Mozambique, landfalls were mostly ITC (31 %) followed by MTS (23 %). Landfalls of very intense tropical cyclones (VITC) were more common in Mozambique (15 %) than Madagascar (7 %). An average of 1.8 million and 775,000 people per season were exposed to strong cyclone winds in Madagascar and Mozambique, respectively, with economic losses from cyclones per season averaging $544 million in Madagascar and $170 million in Mozambique. The African Risk Capacity (ARC), a specialized agency of the African Union, has implemented a parametric insurance solution to mitigate the proximate effects of cyclones damage on vulnerable populations. Four modules to estimate losses caused by cyclone events are described; the hazard-, vulnerability / damage-, - exposure- and insurance modules. Initial outcomes of the ARC’s parametric cyclone insurance policy in Madagascar and Mozambique are discussed. Since its launch in 2020, the ARC’s parametric cyclone insurance policy including its Replica partner allocated a total payout of $12.2 million to Madagascar following the landfalls of cyclones BATSIRAI in 2022 and FREDDY in 2023.

Destructive destruction or creative destruction? Unraveling the effects of tropical cyclones on economic growth

As tropical cyclones make landfall along coastlines all over the world, havoc is wreaked on families, businesses, economies, etc. A generally overlooked topic is one of the inherent dangers in tropical cyclone landfalls. These can produce tornadoes in the spiral rain bands coming ashore by encountering increasingly higher frictional convergence. The second component will be assessing which other parameters could be analyzed on a synoptic timescale to evaluate how we can potentially improve longer term predictions of tropical cyclone (TC)-induced tornadogenesis. The analysis showed that the combination of high low-level moisture, vertical temperature gradients, and enhanced vertical wind shear is the key factor that links landfalling tropical cyclones to associated tornadogenesis prior to, during, and/or after the time of landfall. An integral part of the process preceding TC-induced tornadogenesis is the enhanced vertical temperature gradient that develops as the storm maintains warm-core characteristics aloft but develops cold-core characteristics closer to the surface. The examination of forecaster perspectives showed that over the past few years there is strong evidence of forecaster improvement based upon greater cognizance of forecast variables linked to TC-induced tornadoes.

The mean kinematic and thermodynamic structures of tropical cyclones (TCs) making landfall in mainland China are examined by using sounding data from 1998 to 2009. It is found that TC landfall is usually accompanied with a decrease in low-level wind speed, an expansion of the radius of strong wind, weakening of the upper-level warm core, and drying of the mid-tropospheric air. On average, the warm core of the TCs dissipates 24 h after landfall. The height of the maximum low-level wind and the base of the stable layer both increase with the increased distance to the TC center; however, the former is always higher than the latter. In particular, an asymmetric structure of the TC after landfall is found. The kinematic and thermodynamic structures across various areas of TC circulation differ, especially over the left-front and right-rear quadrants (relative to the direction of TC motion). In the left-front quadrant, strong winds locate at a smaller radius, the upper-level temperature is warmer with the warm core extending into a deep layer, while the wet air occupies a shallow layer. In the right-rear quadrant, strong wind and wet air dwell in an area that is broader and deeper, and the warmest air is situated farther away from the TC center.

Since 1998, several institutions have deployed mobile instrumented towers to collect research-grade meteorological data from landfalling tropical cyclones. This study examines the wind flow characteristics from seven landfalling tropical cyclones using data collected from eight individual mobile tower deployments which occurred from 1998-2005. Gust factor, turbulence intensity, and integral scale statistics are inspected relative to changing surface roughness, mean wind speed and storm-relative position. Radar data, acquired from the National Weather Service (NWS) Weather Surveillance Radar - 1988 Doppler (WSR-88D) network, are examined to explore potential relationships with respect to radar reflectivity and precipitation structure (convective versus stratiform). The results indicate tropical cyclone wind flow characteristics are strongly influenced by the surrounding surface roughness (i.e., exposure) at each observation site, but some secondary storm dependencies are also documented.

ABSTRACTChina faces the Northwest Pacific with the world's most active tropical cyclones (TCs). Whether and how the warming of the “Roof of the World”, the Tibetan Plateau (TP), influences the environmental field and precipitation of landfalling TC (LTC) remains unclear. In this study, a data‐driven objective classification reveals that the key environmental field influencing the LTC precipitation in China is closely related to the TP‐related high pressure. The precipitation rate of LTC in China exhibits an overall increasing trend over the past 43 years under TP warming. However, the trend of the precipitation rate depends on environmental fields. For LTCs affecting southeastern China, the South Asian High (SAH) intensifies and extends eastward, the Western Pacific Subtropical High (WPSH) shifts westward but weakens, stabilizing the atmosphere and reducing precipitation rate. For LTCs impacting southern China, the SAH and WPSH strengthen, increasing atmospheric instability and enhancing precipitation rate.